Use of heating instrument for shoes

ABSTRACT

The present application discloses a shoe heating apparatus including abase with a heating unit, and a thermally insulative body, wherein the bottom of the base is shaped as bottom of a foot such that it fits with a shoe sole.

BACKGROUND ART

Many boots and shoes have an upper formed from a flexible sheet materialsuch as imitation leather or real leather, with a base of the uppermounted on a sole molded from a polymer plastic or rubber material. Theuse of synthetic materials in the manufacture of soles for boots andshoes is already well established. PVC, polyurethane, EVA andthermoplastic rubber have all been used to fulfill this purpose. Thesesynthetic materials have suitable functional properties and areaesthetically pleasing as well as being comfortable. Rubber, however, isparticularly sought after because of its durability, its resistance tohydrolysis and bacterial attack and its thermal resistance.

During the production process the upper is typically formed around aforming last in a first manufacturing step and then the sole isinjection molded onto a base (i.e. insole) of the upper in a secondmanufacturing step. The forming last provides a template for thethree-dimensional size and shape of the upper. Accordingly, the firststep involves mainly shaping and stitching the upper. As there isgenerally no heating involved in this step the last can be made from avariety of materials, including non-thermally conductive material. Woodand metal have traditionally been used, and more recently plastic.Plastic is particularly preferred in lasts today because it is easy toform into the desired shape and is also relatively inexpensive.

The second manufacturing step in the conventionally practiced productionprocess involves injection molding of the outsole onto the base of theupper. As mentioned above, several synthetic materials have been knownto be used for the outsole. Rubber, however, is seen as beingparticularly attractive and so-called twin density rubber soles areparticularly desirable because they provide a tough outsole and aresilient midsole. Twin density rubber soles therefore provide a durablewear surface at the outsole while maintaining cushioned comfort for thewearer with the resilient midsole. Expanded vulcanized rubber in themid-sole contains cavities or cells (either open or closed) which givethe mid-sole its desired level of resilience.

This process requires an intermediate step of removing the upper fromthe forming last and transferring the upper to the injection moldingassembly. This process has the disadvantage that it is very laborintensive and can easily add 25% to the manufacturing cost for a pair ofshoes. Not only may this create an unsatisfactory product but it mayalso delay production while the problem is rectified.

It would therefore be highly desirable to provide a method ofintegrating the production process steps of creating footwear that wouldclearly streamline the production process and reduce the productioncosts.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given herein below, and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein;

FIG. 1 is a schematic sectioned side view of basic shoe heatinginstrument.

FIG. 2 is a schematic sectioned side view of the forming/heating last.

DISCLOSURE OF THE INVENTION

In the present application, “a” and “an” are used to refer to bothsingle and a plurality of objects.

As used herein, a “sole” refers to an outsole or midsole that fuses withthe upper.

As used herein, a “shoe heating instrument” or “heating instrument” or“instrument” is used to heat the bottom of the shoe upper so that thesole or the upper bottom that has the hot melt adhesive applied on it,will melt and cool and cause a strong bond between the sole and thebottom of the upper. This is achieved by inserting the shoe heatinginstrument into the opening of the shoe upper and allowing theinstrument to settle in whereby the bottom of the instrument is heated.The shoe heating instrument is similar to a shoe last in that at aminimum the bottom of the instrument is shaped so that the bottom of theshoe upper and the sole that contacts the bottom of the shoe upper fitwell together within the shape of the bottom of the instrument. In thisregard, the heating last can be considered to be a more complicatedversion of a shoe heating instrument, but the common feature between theheating last and heating instrument is that the base of the heatinginstrument is required to be particularly shaped to fully receive andfit the sole to the bottom of the upper, and that the base of theinstrument can be heated such as by thermal conduction or induction.

Thus, as used herein, whenever “heating instrument” is used, “heatinglast” is also contemplated within the scope of the terminology in that apre-templated heating base is used to fuse upper with the sole.

As used herein, a shoe “last” refers to a “forming last” or “heating orheated last”. “Heating last” and “heated last” are used interchangeablyin the present application.

As used herein, a “forming last” is used to shape the shoe upper.

As used herein, a “heating or heated last” is used to heat the bottom ofthe shoe upper so that the sole that has the hot melt adhesive appliedon it, will melt and cool and cause a strong bond between a sole and thebottom of the upper. This is achieved by inserting the heating or heatedlast into the opening of the shoe upper and allowing the last to settlein whereby the bottom of the last is heated. Alternatively, the heatinglast can serve as a forming last. After the shoe upper is shaped by theforming last, and without removing the last from the upper, a heat plateon the bottom is heated while a hot melt film adhesive applied sole isheld in place fitted into close contact with the bottom of the upper.The heat from the heating last melts the adhesive, and a strong bond isformed between the shoe upper and the sole.

On occasion, perhaps an upper is made without necessarily using aforming last, in which case if it is desired to fuse the sole to theupper, the sole can be brought juxtaposed to the bottom of the upper andthe heating last or heating instrument can be used to heat the hot meltadhesive placed on the sole to make the shoe.

In one aspect, the present invention is directed to a shoe heatingapparatus comprising a base with a heating unit, and a thermallyinsulative body, wherein bottom of the base is shaped as bottom of afoot such that it fits with a shoe sole. The body may be a shoe last.And the heating unit may be thermally inductive or conducive unit.

In another aspect, the present invention is directed to a method offusing upper of a shoe to a sole, comprising the steps of:

(i) contacting a pre-formed rubber sole on to the bottom of a pre-formedupper, wherein either or both of the pre-formed rubber sole or thepre-formed upper is covered with heat sensitive adhesive such as hotmelt film adhesive on the sides of the pre-formed rubber sole or thepre-formed upper that are desired to be contacted with each other so asto form a permanent bond;

(ii) inserting a heating instrument having a body and a base to theupper;

(iii) heating the base of the instrument, while substantially preventingthe heating of parts of the body other than the base, resulting in themelting of the heat-sensitive adhesive; and

(iv) allowing the shoe upper and sole to cool down, whereupon permanentbond is established between them. Steps (i) and (ii) may be reversed.Preferably, non-woven fabric is placed between the sole and upper. Theshoe may be an athletic shoe, but all manner of shoes are contemplatedby the present invention. The heating instrument may be heating last.

In another aspect, the present invention is directed to a method offusing upper of a shoe to a sole, comprising the steps of:

making an upper around the shoe last described above, having a body anda base with a heating unit;

contacting a pre-formed rubber sole on to bottom of the upper, whereineither or both of the pre-formed rubber sole or the upper is coveredwith heat sensitive adhesive such as hot melt film adhesive on the sidesof the pre-formed rubber sole or the upper that are desired to becontacted with each other so as to form a permanent bond;

heating the base of the shoe last, while substantially preventing theheating of parts of the body other than the base, resulting in themelting of the heat-sensitive adhesive; and

allowing the shoe upper and sole to cool down, whereupon permanent bondis established between them. Non-woven fabric may be placed between thesole and upper. The shoe may be a boot, athletic shoe, or walking shoeor any other type of shoe that uses a last to make an upper.

In another aspect, the present invention is directed to a method offusing upper of a shoe to a sole, comprising the steps of:

making an upper around the a forming last;

removing the forming last from the upper;

inserting a heating instrument having a body and a base to the upperdescribed above;

contacting a pre-formed rubber sole on to bottom of the upper, whereineither or both of the pre-formed rubber sole or the upper is coveredwith heat sensitive adhesive such as hot melt film adhesive on the sidesof the pre-formed rubber sole or the upper that are desired to becontacted with each other so as to form a permanent bond;

heating the base of the shoe last, while substantially preventing theheating of parts of the body other than the base, resulting in themelting of the heat-sensitive adhesive; and

allowing the shoe upper and sole to cool down, whereupon permanent bondis established between them. Non-woven fabric may be placed between thesole and upper. The shoe may be a boot, athletic shoe, or walking shoeor any other type of shoe that uses a last to make an upper.

In another aspect, the present invention directed to shoes that are madefrom the processes described above.

According to an aspect of the present invention, there is provided amethod of making an item of footwear such as a shoe such as athleticfootwear or a boot, comprising the steps of:

forming an upper for the item of footwear on a forming last, the forminglast including a body having the general shape of a foot around whichthe upper of the footwear item is to be formed, the body having a basecorresponding in shape to a sole of the foot;

bonding a pre-formed rubber sole on to the bottom of the pre-formedupper, wherein either or both of the pre-formed rubber sole or thepre-formed upper is applied with heat sensitive adhesive such as hotmelt film adhesive on the sides of the pre-formed rubber sole or thepre-formed upper that are desired to be contacted with each other so asto form a permanent bond; and

heating the bottom of the formed upper while the upper is still mountedon the forming last, wherein the step of heating the forming lastincludes heating the base of the last body, while substantiallypreventing the heating of parts of the body other than the base,resulting in the melting of the heat-sensitive adhesive, and whereuponcooling the shoe upper and sole, permanent bond is established betweenthe sole and the upper.

In the above process, the heating last may be also used as a forminglast for the upper. Or, the heated last and forming last may bedifferent or separately used. In certain situations, for instance in thecase of certain types of athletic footwear that do not require a forminglast to shape the upper, only the heated last or a heating instrumentmay be needed to fuse the sole to the upper. The instrument or last maybe inserted into the pre-formed upper and the base of the last orinstrument may be heated.

As mentioned above, the inventive method is directed to fusing apre-formed sole to an upper using a heated last or a heating instrumentin the manner as described above. That is, the instrument is heated atthe base portion as it comes into contact with the bottom portion of thepre-formed upper as the sole is fitted to the bottom of the upper,wherein the heat sensitive adhesive is layered between bottom of theupper and the sole.

A Tricot machine may be used in which a sole is positioned underneaththe bottom of the upper, a heating instrument is inserted into the upperand is pressed down on the bottom of the upper where the bottom of theupper is in contact with the sole such that when the instrument isheated, a bond between the shoe upper and the sole is formed through themelting of a hot melt adhesive film juxtaposed between the bottom of theupper and the sole.

Preferably, non-woven textile that is made of entangled thin layers offiber can be laminated as a cheap carrier to bind the sole or outsole tothe upper. The melting temperature of hot-melt film and the varioustypes of polymers used can be determined using known tables.

Conventionally, in certain situations, the last has been used to heatcertain portions of a shoe upper. For example, the toe area could beheated to cause a certain shape, or the heel area could be heated toeffectuate a certain shape as to the upper. However, the heated last hadnot, been conventionally used to fuse the upper to the sole in themanner as in the present invention.

While conventional thermal conduction heating mechanism may be used,induction heat can be used as another mechanism of heating theinstrument. This is exemplified in U.S. Pat. No. 8,959,690, which isincorporated by reference herein as to the disclosure of inductionmechanism of heating a last.

In a preferred form of the present invention the method includes thestep of heating the forming last before and/or during the step ofbonding the rubber sole onto the formed upper. The forming lasttypically includes a body mimicking the general shape of a foot, aroundwhich body the upper of the item of footwear is formed. Furthermore, thebody typically has a base corresponding in shape as a template to a soleof the foot. In a preferred form of the invention, the step of heatingthe forming last includes heating the base of the last body.

It is to be appreciated that the present invention also extends to anitem of footwear made in accordance with the method described above.

According to another aspect of the present invention there is providedan apparatus for making an item of footwear such as a shoe or a boot,including: a forming last comprising a body as a template for forminggeneral shape of a foot around which an upper is to be formed, the bodyof the last having a base corresponding to a sole of the foot comprisinga heating unit, and the rest of the body is made of insulating materialso as to isolate the heat to the base portion of the last.

Thus, with the apparatus of the invention it is not necessary to removethe shoe or boot upper from the last before the rubber sole is bondedonto the upper. Rather, the apparatus comprises heating element forsupplying necessary heat to the forming last or instrument toefficaciously and quickly bind the rubber sole. Optionally, the forminglast and the heated last may be different, in which case the upper wouldbe removed from the forming last, and then a heating instrument, whichmay include a heating last, may be placed inside the shoe upper and thebased heated.

In a preferred embodiment of the invention, the heating base of the lastbody is located within the last. Preferably the base of the last bodyincludes a metallic portion such as one or more metal plate memberdefining an outer surface of the base to which heat is transmissiblefrom the heating unit. The heating unit may include one or moreelectrically activated heating element located inside the last adjacentan inner side of the plate member(s).

According to a further aspect of the present invention, there isprovided a last for making an item of footwear such as a shoe or a boot,including a body having a template for the general shape of a footaround which an upper of the item of footwear is to be formed, the bodyhaving a base corresponding to a sole of the foot shape and the lastfurther including a heating unit at the base of the last body, andinsulating material to prevent heating parts of the body other than thebase area.

In a preferred embodiment of the invention the base of the last body islocated within the last and is preferably in the form of one or moreelectric heating element and may be built in to the body of the last ormay be plate or plates screwed into the last. The base of the last bodymay include a metallic portion such as a plate member to which heat istransmissible from the heating unit. At least one electrically activatedheating element may be located inside the last adjacent an inner surfaceof the plate member(s). The plate members desirably extend across thebase of the last body.

In a preferred embodiment of the invention the last body includes arecess or cavity for receiving and housing one or more electricallyactivated heating element adjacent to the plate member(s). The body ofthe last is preferably formed predominantly from a plastic such aspolyethylene. The plate member is preferably formed of a material havinggood thermal conductivity, e.g., a metal such as aluminium or steel.

The thermal insulation material serves to insulate parts of the bodyother than the base, such as the non-metallic parts of the body (in thecase of a plastic body, for example) from heat generated by the heatingelement(s).

Furthermore, in a preferred embodiment of the invention the last bodymay comprise two distinct portions; namely, a heel portion and a toeportion. The heel portion and the toe portion are separable from oneanother to facilitate removal of an item of footwear from the last afterthe sole has been molded.

In one aspect, it is contemplated that the heating unit or heatingmember may not need to be a last at all, and may be in the form of abasic heating instrument. An intent of the present invention is fusingof the sole to the bottom of the upper. In this regard, any heating unitmay be used, without necessarily having the body of a last. For example,considering a basic heating instrument, a rod that is attached to aheating plate may be inserted into the upper thereby heating the bottomof the upper, and fusing to the sole by melting of the hot melt adhesivejuxtaposed thereby.

The above and further features and advantages of the present inventionwill be more fully appreciated from the following detailed descriptionof preferred embodiments of the invention with reference to theaccompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIG. 1 of the drawings, each heating instrument (21)includes a holder (20). The holder (20) is formed of a thermal insulatorpredominantly of polyethylene since this material is relativelyinexpensive and can be readily shaped to a specific design. The heatinginstrument (21) has a base (9), which corresponds to a sole of the footshape that the heating instrument (21) is designed to be a template.

The base (9) of the heating instrument includes plate members (13, 14),which extend over the base in each of the heel and toe portions (10, 11)of the heating instrument, respectively. The plate members (13, 14) arepreferably formed from aluminum, which has good thermal conductivityproperties. Other metals, however, may be equally suitable. The platemembers (13, 14) present the outer surface at the base of the heatinginstrument and may be attached to the heating instrument by any suitablefastening, such as screws (27).

The heating instrument also includes a recess (15) for receiving andhousing an electrically activated heating element (16) adjacent an innersurface of each of the heel and toe portion base plate members (13, 14).The heating elements (16) are in face-to-face contact with the platemembers over a substantial proportion of the surface area of those platemembers thereby providing direct and effective heat conduction in asubstantially uniform manner over the plate members. The recess (15)also includes insulation material (17) provided on the side of theelectric heating elements opposite the base plate members (13, 14) tothermally shield the polyethylene parts of the heel and toe portions(10, 11) from the heat generated by the heating elements. During thebonding of the rubber sole the base plates (13, 14) of the forming areheated in the range of about 100 degrees C. to 120 degrees C., and theheating elements (16) themselves achieve temperatures even higher. Thenon-metallic parts of the body must therefore be insulated to preventtheir undesirable deformation.

Each of the electric heating elements (16) is electrically connected toan electric power supply. Electric wires or leads (18) extend from eachof the elements (16) to terminals (19) at a top surface of the heatinginstrument (21). These terminals (19) are adapted to operate in amale-female bayonet type coupling for connection to the power supply(not shown). Each heating instrument (21) also includes a thermostat(not shown) to monitor and regulate heating of the plate members (13,14).

With reference to FIG. 2 of the drawings, each last (5) includes a body(8), which mimics or has the general shape of a foot and provides atemplate for the shape and size of a particular style shoe. The body (8)of each forming last is formed predominantly of polyethylene since thismaterial is relatively inexpensive and can be readily shaped to aspecific last design. The last body (8) has a base (9) which correspondsto a sole of the foot shape that the last body is designed to mimic.

The base (9) of the last body includes plate members (13, 14), whichextend over the base in each of the heel and toe portions (10, 11) ofthe last body, respectively. The plate members (13, 14) are preferablyformed from aluminium, which has good thermal conductivity properties.Other metals, however, may be equally suitable. The plate members (13,14) present the outer surface at the base of the last and may beattached to the last body by any suitable fastening, such as screws(27).

The last body (8) also includes a recess (15) for receiving and housingan electrically activated heating element (16) adjacent an inner surfaceof each of the heel and toe portion base plate members (13, 14). Theheating elements (16) are in face-to-face contact with the plate membersover a substantial proportion of the surface area of those plate membersthereby providing direct and effective heat conduction in asubstantially uniform manner over the plate members. The recess (15)also includes insulation material (17) provided on the side of theelectric heating elements opposite the base plate members (13, 14) tothermally shield the polyethylene parts of the heel and toe portions(10, 11) from the heat generated by the heating elements. During thebonding of the rubber sole the base plates (13, 14) of the forming lastare heated in the range of about 100 degrees C. to 120 degrees C., andthe heating elements (16) themselves achieve temperatures even higher.The non-metallic parts of the last body must therefore be insulated toprevent their undesirable deformation.

Each of the electric heating elements (16) is electrically connected toan electric power supply. Electric wires or leads (18) extend from eachof the elements (16) to terminals (19) at a top surface of the last (5).These terminals (19) are adapted to operate in a male-female bayonettype coupling for connection to the power supply (not shown). Each last(5) also includes a thermostat (not shown) to monitor and regulateheating of the plate members (13, 14).

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described herein will become apparent tothose skilled in the art from the foregoing description and accompanyingfigures. Such modifications are intended to fall within the scope of theappended claims. The following examples are offered by way ofillustration of the present invention, and not by way of limitation.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention specifically described herein. Suchequivalents are intended to be encompassed in the scope of the claims.

What is claimed is:
 1. A shoe heating apparatus comprising a base with a heating unit, and a thermally insulative body, wherein bottom of the base is shaped as bottom of a foot such that it fits with a shoe sole.
 2. The apparatus of claim 1, wherein the body is a shoe last.
 3. The apparatus of claim 1, wherein the heating unit is thermally inductive unit.
 4. The apparatus of claim 1, wherein the heating unit is thermally conductive unit.
 5. A method of fusing upper of a shoe to a sole, comprising the steps of: contacting a pre-formed rubber sole on to the bottom of a pre-formed upper, wherein either or both of the pre-formed rubber sole or the pre-formed upper is covered with heat sensitive adhesive such as hot melt film adhesive on the sides of the pre-formed rubber sole or the pre-formed upper that are desired to be contacted with each other so as to form a permanent bond; inserting a heating instrument having a body and a base to the upper; heating the base of the instrument, while substantially preventing the heating of parts of the body other than the base, resulting in the melting of the heat-sensitive adhesive; and allowing the shoe upper and sole to cool down, whereupon permanent bond is established between them.
 6. The method of claim 5, wherein non-woven fabric is placed between the sole and upper.
 7. The method of claim 5, wherein the shoe is an athletic shoe.
 8. The method of claim 5, wherein the heating instrument is heating last.
 9. A method of fusing upper of a shoe to a sole, comprising the steps of: making an upper around the shoe last of claim 2, having a body and a base with a heating unit; contacting a pre-formed rubber sole on to bottom of the upper, wherein either or both of the pre-formed rubber sole or the upper is covered with heat sensitive adhesive such as hot melt film adhesive on the sides of the pre-formed rubber sole or the upper that are desired to be contacted with each other so as to form a permanent bond; heating the base of the shoe last, while substantially preventing the heating of parts of the body other than the base, resulting in the melting of the heat-sensitive adhesive; and allowing the shoe upper and sole to cool down, whereupon permanent bond is established between them.
 10. The method of claim 9, wherein non-woven fabric is placed between the sole and upper.
 11. The method of claim 9, wherein the shoe is a boot, athletic shoe, or walking shoe.
 12. A method of fusing upper of a shoe to a sole, comprising the steps of: making an upper around the a forming last; removing the forming last from the upper; contacting a heating instrument having a body and a base to the upper of claim 1; contacting a pre-formed rubber sole on to bottom of the upper, wherein either or both of the pre-formed rubber sole or the upper is covered with heat sensitive adhesive such as hot melt film adhesive on the sides of the pre-formed rubber sole or the upper that are desired to be contacted with each other so as to form a permanent bond; heating the base of the shoe last, while substantially preventing the heating of parts of the body other than the base, resulting in the melting of the heat-sensitive adhesive; and allowing the shoe upper and sole to cool down, whereupon permanent bond is established between them.
 13. The method of claim 12, non-woven fabric is placed between the sole and upper.
 14. The method of claim 12, wherein the shoe is a boot, athletic shoe, or walking shoe.
 15. A shoe made using the method of claim
 5. 16. A shoe made using the method of claim
 9. 17. A shoe made using the method of claim
 12. 18. A complex comprising the apparatus of claim 1 in association with a shoe upper and sole. 